JP2012002951A - Imaging device, method for detecting in-focus position and in-focus position detection program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging device, a method for detecting an in-focus position and an in-focus position detection program that allow an AF operation to be appropriately executed without losing sight of the in-focus position focused to a subject position.SOLUTION: A CPU block 1043 of a digital still camera processor 104 is configured to perform functions as a movement detecting section 201, an estimating section 202, an in-focus position detecting range setting section 203 and an in-focus position detecting section 204. The movement detecting section 201 detects a movement of an image based upon differences in a plurality of image data time-series output from a CCD 101, and the estimating section 202 estimates a movement of a subject or a photographer based upon the detected movement of the image. The in-focus position detecting range setting section 203 sets an in-focus position detection range (a moving range of a focus lens 42a) in accordance with the estimated movement of the subject or the photographer. The in-focus position detecting section 204 detects the in-focus position while moving the focus lens 42a within the set in-focus position detection range.

Description

  The present invention relates to an imaging apparatus having an autofocus function for automatically focusing on a subject, a focus position detection method, and a focus position detection program.

  An imaging apparatus such as a digital still camera generally has an autofocus (hereinafter referred to as “AF”) function for automatically focusing on a subject. As a control method of the AF operation, hill-climbing AF control is widely known (for example, see Patent Document 1). In this hill-climbing AF control, an integrated value of the luminance difference of the neighboring pixels is obtained from the image data output from the image sensor, and this integrated value of the luminance difference is used as an AF evaluation value indicating the degree of focus. When the subject is in focus, the outline of the subject is clear and the brightness difference between adjacent pixels increases, so the AF evaluation value increases. On the other hand, in the out-of-focus state, the contour portion of the subject is blurred and the luminance difference between pixels becomes small, so the AF evaluation value becomes small. When executing the AF operation, the AF evaluation values are sequentially acquired while moving the focus lens in the optical axis direction. When the AF evaluation value becomes the largest, that is, with the peak position as the in-focus position, the focus lens is moved. Stop.

  In recent years, a subject tracking function for tracking a main subject in an image has been put to practical use as a digital still camera technique. The subject tracking function detects, for example, the amount and direction of movement of a subject by template matching using image data of a subject image to be tracked as a template, and an AF operation target area (in accordance with the movement of the subject) ( (Hereinafter referred to as “AF area”), and the AF operation and exposure condition calculation can be performed following the moving subject (see, for example, Patent Documents 2 and 3).

  However, in a conventional imaging apparatus having a subject tracking function, the AF area in the image can be moved following the movement of the subject, but the subject is in the depth direction of the image (the direction toward the photographer or the direction away from the photographer). ), The focus position may be lost during the AF operation. In other words, when the AF operation is executed using the position of the subject to be tracked as the AF area, the movement range of the focus lens for obtaining the AF evaluation value is limited in order to execute the AF operation at high speed in consideration of the movement of the subject. is doing. At this time, if the subject has moved in the depth direction of the image, the focus position of the subject may be outside the focus lens movement range, resulting in loss of focus position.

  The present invention has been made in view of the above, and an imaging apparatus, a focus position detection method, and a focus position that can appropriately execute an AF operation without losing sight of the focus position focused on the subject position. It aims to provide a detection program.

  In order to solve the above-described problems and achieve the object, an imaging apparatus according to the present invention includes a focus lens, an imaging element that receives light incident through the focus lens and outputs image data, and the imaging A motion detection unit that detects a motion of an image based on a difference between a plurality of image data output in time series from the element; and a motion of a subject or a photographer based on the motion of the image detected by the motion detection unit Estimating means for estimating the moving range setting means for setting the moving range of the focus lens in accordance with the movement of the subject or the photographer estimated by the estimating means, and the moving range set by the moving range setting means. A focus position detecting means for detecting a focus position in focus with respect to the subject position of the image by moving the focus lens in the optical axis direction And wherein the door.

  In addition, a focus position detection method according to the present invention is a focus position that is executed in an imaging apparatus that includes a focus lens and an image sensor that receives light incident through the focus lens and outputs image data. A detection method comprising: detecting a motion of an image based on a difference between a plurality of image data output in time series from the imaging device; and a motion of a subject or a photographer based on the detected motion of the image Estimating the movement of the focus lens in accordance with the estimated movement of the subject or the photographer, moving the focus lens in the optical axis direction within the set movement range, and Detecting an in-focus position that is in focus with respect to the subject position.

  In addition, an in-focus position detection program according to the present invention includes a focus lens and an imaging device that receives light incident through the focus lens and outputs image data. A function of detecting the movement of an image based on a difference between a plurality of image data output in series, a function of estimating the movement of a subject or a photographer based on the detected movement of the image, and the estimated subject or shooting A function for setting the movement range of the focus lens in accordance with the movement of the person, and a focus position where the focus lens is moved in the optical axis direction within the set movement range and focused on the subject position of the image Is a program for realizing

  According to the present invention, the movement range of the focus lens is set according to the movement of the subject or the photographer estimated from the movement of the image, and the in-focus position is detected while moving the focus lens within the set movement range. Therefore, there is an effect that the AF operation can be appropriately executed without losing sight of the in-focus position in focus on the subject position.

FIG. 1-1 is a top view of the digital still camera. FIG. 1-2 is a front view of the digital still camera. FIG. 1C is a back view of the digital still camera. FIG. 2 is a block diagram showing the configuration of the control system of the digital still camera. FIG. 3 is a diagram for explaining an example of the AF area. FIG. 4 is a functional block diagram of a CPU block in the digital still camera processor. FIG. 5 is a main flowchart showing the overall flow of the AF operation executed in the digital still camera. FIG. 6 is a diagram illustrating an example of a focus lens driving method in the focus position detection process and an AF evaluation value acquired in the normal AF mode. FIG. 7 is a flowchart showing the details of the focus position detection process in the normal AF mode. FIG. 8 is a diagram for explaining the area display processing. FIG. 9 is a flowchart showing details of the focus position detection process in the tracking AF mode. FIG. 10 is a diagram illustrating a state in which an image is divided into a plurality of divided regions. FIG. 11 is an image diagram regarding motion detection in a divided area. FIG. 12 is a flowchart showing details of the motion detection determination process. FIG. 13 is a diagram for explaining an image motion pattern in a divided area including an AF area. FIG. 14 is a diagram illustrating the movement of the tracking area that is the range in which template matching is performed. FIG. 15 is a flowchart showing details of the focus position detection range setting process. FIG. 16 is a diagram for explaining an example of the reference range of the focus position detection range in the AF mode. FIG. 17 is a diagram illustrating an example of the number of pulses to be added to the reference range of the focus position detection range. FIG. 18 is a diagram illustrating a driving method of the focus lens in a case where the focus position detection range is made variable in accordance with the movement of the subject during AF in the tracking AF mode. FIG. 19 is a diagram showing an image of a series of processing when the subject is moving by the movement of the pattern P1. FIG. 20 is a diagram showing an image of a series of processes when the subject is moving by the movement of the pattern P2. FIG. 21 is a diagram showing an image of a series of processes when the subject is moving by the movement of the pattern P3. FIG. 22 is a flowchart showing details of motion detection determination processing in the second embodiment. FIG. 23 is a diagram for explaining a movement pattern of each divided area when the photographer moves the digital still camera to change the composition of the subject. FIG. 24 is a diagram for explaining a movement pattern of each divided region when the photographer performs a panning shot of a moving subject. FIG. 25 is a diagram for explaining a movement pattern of each divided region when the photographer moves in a direction of approaching and separating from a stationary subject. FIG. 26 is a flowchart showing details of the focus position detection range setting process in the second embodiment. FIG. 27 is a diagram showing an image of a series of processes when the photographer moves the digital still camera to change the composition of the subject. FIG. 28 is a diagram showing an image of a series of processes when the photographer is taking a panning shot of a subject that is moving away. FIG. 29 is a diagram illustrating an image of a series of processes when the photographer is moving toward the subject.

  Exemplary embodiments of an imaging apparatus, a focus position detection method, and a focus position detection program according to the present invention will be described below in detail with reference to the accompanying drawings. Although an example in which the present invention is applied to a digital still camera will be described below, the present invention can be widely applied to any type of imaging apparatus having a function of performing an AF operation while tracking a subject. .

(Configuration of digital still camera)
FIG. 1 is a diagram illustrating an appearance of a digital still camera according to the present embodiment, FIG. 1-1 is a top view of the digital still camera, FIG. 1-2 is a front view of the digital still camera, and FIG. Is a back view of the digital still camera.

  As shown in FIG. 1A, the digital still camera according to the present embodiment has a sub liquid crystal display (hereinafter, the liquid crystal display is referred to as “LCD”) 1 that displays the number of still images that can be taken on its upper surface. And release shutter SW1 that is pressed during still image shooting, and switching between various modes such as a recording (shooting) mode for recording an image, a playback mode for playing back a recorded image, and a SETUP mode for camera settings. A mode dial SW2 that is operated during the operation.

  Also, as shown in FIG. 1-2, the digital still camera according to the present embodiment has a strobe light emitting unit 2 that emits a strobe on the front surface and a remote control light receiving unit 3 that receives an infrared signal from a remote control terminal (not shown). And a lens barrel unit 4 and an optical finder (front surface) 5. Further, on the side surface of the digital still camera according to the present embodiment, a memory card throttle for inserting a memory card, which will be described later, and a battery accommodating portion for accommodating a battery are provided. The memory card throttle and the battery accommodating portion are lid bodies. 6 is occluded.

  Also, as shown in FIG. 1C, the digital still camera according to the present embodiment has an AF LED 7 that is turned on during AF operation, a strobe LED 8 that is turned on during strobe light emission, and various setting screen display and playback images as shown in FIG. LCD monitor 9 used as an electronic finder at the time of display and photographing, an optical finder (back surface) 10, and a power switch 11.

  Further, on the back surface of the digital still camera according to the present embodiment, a zoom (WIDE) switch SW3 operated during wide-angle zoom, a zoom (TELE) switch SW4 operated during telephoto zoom, and a self-timer are operated. Self-timer / deletion switch SW5, menu switch SW6 operated when selecting a menu, operated when switching strobe modes (automatic, forced flash, red-eye reduction, etc.) and moving the cursor on the LCD monitor 9 up Up / strobe switch SW7, which is operated when moving the cursor, right switch SW8 which is operated when the cursor on the LCD monitor 9 is moved to the right, display switch SW9 which is operated when switching the display of the LCD monitor 9, and macro photography The LCD monitor 9 The down / macro switch SW 10 that is operated when the sol is moved downward, and the left that is operated when the photographed image is confirmed on the LCD monitor 9 and the cursor on the LCD monitor 9 is moved to the left. There are provided various switches such as an image confirmation switch SW11, an OK switch SW12 that is operated when a selected item is confirmed, and a quick access switch SW13 that is operated when a registered menu is selected.

  FIG. 2 is a block diagram illustrating a configuration of a control system of the digital still camera according to the present embodiment. The digital still camera according to this embodiment performs digital processing by pre-processing an analog electrical signal output from the CCD 101 and a CCD 101 that photoelectrically converts light incident through the lens barrel unit 4 and outputs the electrical signal. A digital still camera processor (hereinafter simply referred to as a “processor”) that processes and controls various operations of the digital still camera by processing digital signals from the F / E (front end) -IC 102 that is output as signals and the F / E-IC 102. .) 104.

  The lens barrel unit 4 includes a zoom optical system 41 including a zoom lens 41a and a zoom motor 41b for capturing an optical image of a subject, a focus optical system 42 including a focus lens 42a and a focus motor 42b, an aperture 43a and an aperture motor 43b. A diaphragm unit 43, a mechanical shutter unit 44 including a mechanical shutter 44a and a mechanical shutter motor 44b, and a motor driver 45 for driving each motor are provided. The motor driver 45 is driven and controlled by a drive command from a CPU block 1043 described later in the processor 104.

  The CCD 101 is a solid-state imaging device that receives light incident through the lens barrel unit 4 and photoelectrically converts the optical image to output image data corresponding to the optical image. In the digital still camera according to the present embodiment, the CCD 101 is used as the image sensor, but another image sensor such as a CMOS image sensor may be used instead of the CCD 101.

  The F / E-IC 102 includes a CDS 1021 that performs correlated double sampling for image noise removal, an AGC 1022 that performs gain adjustment, an A / D 1023 that converts an analog signal into a digital signal, and a first CCD signal processing block (described later) in the processor 104. A TG (Timing Generator) 1024 that generates drive timing signals for the CCD 101, the CDS 1021, the AGC 1022, and the A / D 1023 based on the vertical synchronization signal (VD signal) and the horizontal synchronization signal (HD signal) supplied from the H.1041. The operation of each unit in the F / E-IC 102 is controlled by a CPU block 1043 described later in the processor 104.

  The processor 104 includes a first CCD signal processing block 1041, a second CCD signal processing block 1042, a CPU block 1043, a local SRAM 1044, a USB block 1045, a serial block 1046, a JPEG / CODEC block 1047, a RESIZE block 1048, and a TV signal display. A block 1049 and a memory card controller block 10410 are included. The above-described units in the processor 104 are connected to each other via a bus line.

  The first CCD signal processing block 1041 performs white balance correction and gamma correction on the image data input from the CCD 101 via the F / E-IC 102, and controls the timing of the image data. The HD signal is supplied to the TG 1024. The second CCD signal processing block 1042 converts the input image data into luminance data / color difference data by filtering processing.

  The CPU block 1043 controls operation of each unit of the digital still camera according to the present embodiment. Specifically, the CPU block 1043 controls the sound recording operation by the sound recording circuit 1151. The voice recording circuit 1151 records the voice signal converted by the microphone 1153 and amplified by the microphone amplifier 1152 in accordance with a command from the CPU block 1043. The CPU block 1043 also controls the sound reproduction operation by the sound reproduction circuit 1161. In response to a command from the CPU block 1043, the audio reproduction circuit 1161 reproduces an audio signal recorded in an appropriate memory, inputs the audio signal to the audio amplifier 1162, and outputs audio from the speaker 1163. Further, the CPU block 1043 controls the operation of the strobe circuit 114 to emit illumination light from the strobe light emitting unit 2. In addition, the CPU block 1043 performs a process of detecting an in-focus position that is in focus with respect to the subject position as a characteristic process in the present embodiment, which will be described in detail later.

  The CPU block 1043 is connected to the sub CPU 109 arranged outside the processor 104. The sub CPU 109 controls display on the sub LCD 1 via the LCD driver 111. The sub CPU 109 is connected to an operation key unit including the AF LED 7, the strobe LED 8, the remote control light receiving unit 3, the buzzer 113, and the switches SW 1 to SW 13, and outputs an output signal from the operation key unit or the remote control light receiving unit 3 to the user. As operation information, the operation of the AF LED 7, the strobe LED 8, and the buzzer 113 is controlled according to the user operation information, and the user operation information is transmitted to the CPU block 1043 in the processor 104.

  The local SRAM 1044 is a memory that temporarily stores data necessary for control. The USB block 1045 performs USB communication with an external device such as a computer terminal connected to the USB connector 122. The serial block 1046 performs serial communication with an external device such as a computer terminal connected to the RS-232C connector 1232 via the serial driver circuit 1231.

  The JPEG / CODEC block 1047 performs processing for compressing the captured image data in the JPEG format and for expanding the recorded image data compressed in the JPEG format. The RESIZE block 1048 performs processing for enlarging / reducing the size of image data by interpolation processing.

  The TV signal display block 1049 converts the image data into a video signal for display on an external display device such as an LCD monitor 9 or a TV. An LCD driver 117 is connected to the TV signal display block 1049, and an image is displayed on the LCD monitor 9 driven by the LCD driver 117. In addition, when the video signal AMP 118 is connected to the TV signal display block 1049 and the video jack 119 is connected to an external display device such as a TV, an image is displayed on the external display device.

  The memory card controller block 10410 is connected to the memory card throttle 121 and controls a memory card inserted into the memory card throttle 121 and a general-purpose PCMCIA.

  Further, an SDRAM 103, a RAM 107, a ROM 108, and a built-in memory 120 are disposed outside the processor 104, and these are connected to the processor 104 by a bus line.

  The SDRAM 103 is a memory that temporarily stores image data when the processor 104 performs image processing. For example, the stored image data is input to the processor 104 from the CCD 101 via the F / E-IC 102 and “RAW? RGB in a state where white balance correction and gamma correction are performed in the first CCD signal processing block 1041. “Image data”, “YUV image data” in which luminance data / color difference data conversion has been performed in the second CCD control block 1042, “JPEG image data” compressed in JPEG format in the JPEG / CODEC block 1047, etc. is there.

  The ROM 108 stores a control program written in a code readable by the CPU block 1043 and parameters for control. Note that these parameters may be stored in the built-in memory 120. When the power of the digital still camera is turned on, the program is loaded into a main memory (not shown), and the CPU block 1043 controls the operation of each unit according to the program and temporarily stores data necessary for control in the RAM 107 and the processor. The data is stored in a local SRAM 1044 in 104. If a rewritable flash ROM is used as the ROM 108, the control program and parameters for control can be changed, and the function can be easily upgraded.

  The built-in memory 120 is a memory for recording captured image data when no memory card is inserted in the memory card throttle 121. The RAM 107 is a memory used as a work area when the CPU block 1043 executes a control program.

(Overview of digital still camera operation)
Next, an outline of the operation of the digital still camera configured as described above will be described. The operation mode of the digital still camera according to the present embodiment includes a recording mode that is a mode for capturing and recording an image, and a playback mode that reproduces the recorded image. The mode of the AF operation when operating in the recording mode. Further, there are a tracking AF mode in which an AF operation is performed at the subject position while tracking the subject, and a normal AF mode in which AF processing is performed in a predetermined AF area in the center of the image. These operation modes are switched by operating the mode dial SW2. Note that in the shooting standby state in the recording mode (the state before the release shutter SW1 is pressed), a moving image for monitoring is displayed on the LCD monitor 9, and the shooting standby state in the recording mode is particularly in the finder mode. Call it.

  When the power switch 11 is pressed while the mode dial SW2 is in the recording mode, the digital still camera is activated in the recording mode. When the digital still camera is activated in the recording mode, the CPU block 1043 of the processor 104 controls the motor driver 45 to move the lens barrel unit 4 to a position where photographing can be performed. Further, the power is turned on to the respective parts such as the CCD 101, the F / E-IC 102, the LCD display 10 and the like to start the operation. When the power of each part is turned on, the operation in the finder mode is started.

  In the finder mode, the light incident on the CCD 101 through the lens barrel unit 4 is received by the CCD 101, and the optical image is converted into an analog RGB signal and input to the F / E-IC 102. The analog RGB signal is subjected to predetermined processing such as noise reduction processing and gain adjustment processing by the CDS 1021 and the AGC 1022 of the F / E-IC 102, converted into a digital signal by the A / D 1023, and the first signal of the processor 104. This is input to the CCD signal processing block 1041.

  The digital RGB signal input to the first CCD signal processing block 1041 is transferred to the second CCD signal processing block 1042 and converted into YUV image data (luminance data / color difference data) in the second CCD signal processing block 1042. Converted. The YUV image data is written into the frame memory of the SDRAM 103. This YUV image data is read from the frame memory as needed, sent to the TV signal display block 1049, and converted into a video signal. Then, this video signal is supplied to an external display device such as an LCD monitor 9 or a TV, and an image is displayed. In the finder mode, the above processing is performed at 1/30 second intervals, and an image displayed on the LCD monitor 9 or the like (hereinafter referred to as “finder image”) is updated every 1/30 seconds.

  Here, when the release shutter SW1 is pressed, the CPU block 1043 calculates an AF evaluation value indicating the degree of focus of the image captured in the processor 104 and an AE evaluation value indicating the exposure state. The AF evaluation value is an integral value of the luminance difference between adjacent pixels in the AF area. When the AF area is in focus, this integrated value has the highest high-frequency component because the edge portion of the image in the AF area is clear. Using this, during AF operation, the AF evaluation value at the position of each focus lens 42a is acquired while moving the focus lens 42a in the optical axis direction, and the point (peak position) where the value becomes maximum is detected. To do. Also, taking into account the fact that there are multiple points that are maximal, if there are multiple points, determine the magnitude of the AF evaluation value at the peak position, the degree of decrease or increase in the surrounding AF evaluation values, and the most reliable A certain point is set as the in-focus position. Then, a recorded image is taken in a state where the focus lens 42a is moved to the in-focus position.

  The AF area for which the AF evaluation value is calculated during the AF operation differs depending on the AF operation mode. When the AF operation mode is the normal AF mode, as shown in FIG. 3A, a predetermined range in the center of the image, for example, the ratio of the size to the entire image is 40% in the horizontal direction and 30% in the vertical direction. (The hatched area in the figure) is the AF area. On the other hand, when the AF operation mode is the tracking AF mode, as shown in FIG. 3B, for example, the ratio of the size to the entire image is in the range of 20% in the horizontal direction and 20% in the vertical direction (in the figure, A hatched area) is set as an AF area, and the AF area is moved within the screen following the movement of the subject. Further, regarding the range in which the focus lens 42a is moved during AF operation (hereinafter referred to as “focus position detection range”), in the normal AF mode, the entire movable range of the focus lens 42a (closest position to infinite telephoto position). However, in the tracking AF mode, since a high-speed AF operation is required, the focus position is detected within a range limited according to the current position of the focus lens 42a and the focal length (Wide side or Tele side). The range is limited.

  By the way, during the AF operation in the tracking AF mode, the focus position detection range is limited as described above. Therefore, when the subject moves in the depth direction of the image, the focus in the AF area set at the subject position is adjusted. There is a concern that the in-focus position may be lost because the in-focus position is out of the in-focus position detection range. Therefore, in the digital still camera according to the present embodiment, the CPU block 1043 of the processor 104 analyzes the image data (digital RGB signal) input from the CCD 101 via the F / E-IC 102 and moves the subject or the photographer. And an in-focus position detection range during AF operation in the tracking AF mode is set according to the estimation result, so that the in-focus position in focus on the subject can be detected appropriately.

  FIG. 4 is a functional block diagram of the CPU block 1043 for realizing the above-described functions. The CPU block 1043 is stored in the ROM 108 as one of the above-described control programs, for example, and executes the in-focus position detection program loaded in the main memory. 202, each functional configuration of the focus position detection range setting unit 203 and the focus position detection unit 204 is realized.

  The motion detection unit 201 is a processing function that detects a motion (motion vector) of an image based on a difference between a plurality of image data output in time series from the CCD 101 and input from the F / E-IC 102 to the processor 104. .

  The estimation unit 202 is a processing function that estimates the motion of the subject or the photographer based on the motion of the image detected by the motion detection unit 201.

  The in-focus position detection range setting unit 203 is a processing function that sets an in-focus position detection range that is a movement range of the focus lens 42a during the AF operation in accordance with the movement of the subject or the photographer estimated by the estimation unit 202. is there.

  The focus position detection unit 204 moves the focus lens 42a in the optical axis direction within the focus position detection range set by the focus position detection range setting unit 203, and calculates the AF evaluation value at each movement position of the focus lens 42a. This is a processing function that detects the position of the focus lens 42a that is calculated and has the maximum AF evaluation value as the in-focus position with respect to the subject.

  Hereinafter, specific examples of operations of the digital still camera realized by the CPU block 1043 having functions as the motion detection unit 201, the estimation unit 202, the focus position detection range setting unit 203, and the focus position detection unit 204 described above. (Example) will be described in more detail.

(First embodiment)
FIG. 5 is a main flowchart showing the overall flow of the AF operation executed in the digital still camera according to the present embodiment. The flow in FIG. 5 is started when the digital still camera is activated in the recording mode.

  When the flow of FIG. 5 is started, the CPU block 1043 first checks the state of the mode dial SW2, and determines whether the AF operation mode is the tracking AF mode or the normal AF mode ( Step S101). Then, if the AF operation mode is the tracking AF mode (step S101: YES), the CPU block 1043 performs processing for setting an AF area for the tracking AF mode (step S102), and enters the normal AF mode. If so (step S101: NO), processing for setting an AF area for the normal AF mode is performed (step S103). The CPU block 1043 then displays a mark that clearly indicates the AF area set in step S102 (see FIG. 3B) or a mark that clearly indicates the AF area set in step S103 (see FIG. 3A). Then, the image is superimposed on the finder image and displayed on the LCD monitor 9 or the like (step S104).

  Next, the CPU block 1043 monitors the operation of the release shutter SW1 (step S105). While the release shutter SW1 is not pressed (step S105: NO), the above processing is repeated, and when the release shutter SW1 is pressed. (Step S105: YES), the process proceeds to the next step S106.

  In step S106, the CPU block 1043 confirms whether the tracking flag is OFF. This is for confirming whether or not the subject tracking operation is performed when the release shutter SW1 is pressed. If the tracking flag is OFF (step S106: YES), the CPU block 1043 performs the focus position detection process in the normal AF mode (step S107), and the tracking flag is ON. (Step S106: NO), the focus position detection process in the tracking AF mode is performed (step S108). Here, the focus position detection process is an AF evaluation value in the AF area set in step S102 or step S103 at each movement position of the focus lens 42a while moving the focus lens 42a step by step within the focus position detection range. And the focus position is searched by detecting the peak. In the normal AF mode, the focus position detection range in which the focus lens 42a is moved is the entire movable range (closest position to infinity telephoto position) of the focus lens 42a as described above, and the tracking AF mode. In this case, the range is limited around the in-focus position (current position). FIG. 6 shows an example of a driving method of the focus lens 42a in the focus position detection process and an AF evaluation value acquired in the normal AF mode. In the example of FIG. 6, the movement start position of the focus lens 42a in the normal AF mode is the close position, and the close position is a position 30 cm from the digital still camera.

  FIG. 7 is a flowchart showing details of the focus position detection process in the normal AF mode in step S107 of FIG. In the focus position detection process in the normal AF mode, the CPU block 1043 first moves the position of the focus lens 42a to the movement start position by the start position movement process (step S201). Here, it is assumed that the movement start position is the closest position. Although the close position may vary depending on the optical system, generally around 30 cm is preferable.

  Next, the CPU block 1043 moves the focus lens 42a step by step toward the infinite telephoto position by lens driving processing (step S202). Then, an AF evaluation value in the AF area is acquired at each moved position by AF evaluation value acquisition processing (step S203). Here, it is assumed that a pulse motor is used as the focus motor 42b, and the moving distance for one step of the focus lens 42a is converted into the number of drive pulses of the focus motor 42b. Specifically, when the focal length is Wide, the focus motor 42b is driven one pulse at a time, and when the focal length is Tele, the focus motor 42b is driven two pulses at a time to move the focus lens 42a toward the infinite telephoto position. Move. The CPU block 1043 repeatedly performs the lens driving process in step S202 and the AF evaluation value acquisition process in step S203 until the focus lens 42a reaches the infinite telephoto position (step S204: NO), and the focus lens 42a is moved to the infinite telephoto position. When it reaches (step S204: YES), the process proceeds to the next step S205.

  In step S205, the CPU block 1043 performs a focus position determination process. This focus position determination process is a process of determining whether or not the focus position can be detected using the AF evaluation value acquired at each movement position of the focus lens 42a. Specifically, the reliability evaluation as described above is performed on the acquired AF evaluation value, and the peak position in the AF evaluation value is determined. Here, when a reliable peak position is detected, the position of the focus lens 42a is stored in the local SRAM 1044 or the like as the focus position, and it is determined that the focus is OK. On the other hand, if no reliable peak position is detected, it is determined that the focus is NG.

  Finally, the CPU block 1043 performs area display processing (step S206), and ends the focus position detection processing in the normal AF mode. In the area display processing, when it is determined that the in-focus state is determined to be in-focus in the in-focus determination processing in step S205, as shown in FIG. 8A, a focusing frame F that clearly indicates the in-focus position is superimposed on the viewfinder image. If it is displayed on the LCD monitor 9 or the like and determined to be in focus NG in the focus determination process in step S205, a finder image on which the focus frame is not superimposed is displayed on the LCD monitor as shown in FIG. This is a process of displaying the image on 9 etc.

  FIG. 9 is a flowchart showing details of the focus position detection process in the tracking AF mode in step S108 of FIG. In the focus position detection process in the tracking AF mode, the CPU block 1043 first performs a motion detection determination process (step S301). That is, in the tracking AF mode, the motion detection unit 201 performs processing for detecting image motion. Therefore, it is determined what type of image motion is detected by the motion detection processing by the motion detection unit 201. . Various techniques have been proposed for image motion detection, and any known technique can be employed. Here, the image motion is detected by template matching as described below.

  The motion detection unit 201 divides an image into a plurality of divided regions and performs a motion detection process for each divided region. Specifically, as shown in FIG. 10, for example, the motion detection unit 201 divides an image into three equal parts in the vertical direction and the horizontal direction and divides the image into nine divided areas A1 to A9. Then, image data continuously acquired at timing synchronized with the VD signal (a plurality of image data output in time series from the CCD 101) is stored in the buffer memory of the SDRAM 103, and each of the nine divided areas A1 to A9 is stored. Thus, the movement is detected by checking how much the change occurs between a plurality of consecutive images. Specifically, the previous image data is stored in the buffer memory, and each of the nine divided areas of the stored image data and the nine divided areas of the image data acquired at the latest timing is expressed by a number. The pixels are moved relative to each other in the diagonal direction up, down, left, and right, and the pixel difference between the image data at each position is obtained. The movement to the position where the result of the pixel difference is the smallest is taken as the image motion. Here, it is desirable that the number of pixels to be moved is variable depending on the arithmetic processing speed of the CPU block 1043.

  FIG. 11 is an image diagram regarding motion detection in the divided region A1. As a result of motion detection as shown in FIG. 11 (a), it is confirmed at which position the pixel difference result is the smallest, and the motion direction is output as shown in FIG. 11 (b). In the example of FIG. 11, the pixel difference result becomes the smallest at the position where the divided area A1 of the image data acquired at the latest timing is moved in the right direction with respect to the previous image data. Output as direction. Although only the movement direction is output in FIG. 11B, it is possible to detect how many pixels the position where the pixel difference result is smallest is shifted and output the amount of movement of the image. desirable. The motion detection unit 201 performs the above processing for each divided region, and detects the motion of the image for each divided region. Then, the estimation unit 202 of the CPU block 1043 performs the motion detection determination process in step S301 of FIG. 9 using the result of the motion detection process by the motion detection unit 201 described above.

  FIG. 12 is a flowchart showing details of the motion detection determination process in step S301 of FIG. First, the estimation unit 202 performs a motion detection area search process (step S401). This is to determine which one of the moving directions of the image is in the divided area including the AF area (here, the divided area A5 at the center of the image). Regarding the direction of movement, it can be divided into several patterns. FIG. 13 shows an example of the pattern. The movement in the direction opposite to the gravitational direction (upward direction as image data) as shown in FIG. 13A is the pattern P1, and the gravitational direction (image is shown in FIG. 13B). As data, the movement in the lower direction) is set as a pattern P2, and the movement in the left and right direction is set as a pattern P3 as shown in FIG. The determination unit 202 determines whether or not the subject is moving by determining which of the above patterns P1 to P3 corresponds to the movement of the image in the divided area including the AF area. As a distance, it is estimated whether it is moving in the direction approaching the photographer or moving away from the photographer.

  That is, the estimating unit 202 first determines whether or not the image motion in the divided area including the AF area corresponds to the pattern P1 (step S402), and if it corresponds to the pattern P1 (step S402: YES). It is estimated that the subject is moving in the direction approaching the photographer (step S403). On the other hand, when the direction of image movement in the divided area including the AF area does not correspond to the pattern P1 (step S402: NO), the estimating unit 202 next performs the image in the divided area including the AF area. It is determined whether or not the movement corresponds to the pattern P2 (step S404). If the movement corresponds to the pattern P2 (step S404: YES), it is estimated that the subject is moving away from the photographer (step S404). S405). On the other hand, when the direction of image motion in the divided area including the AF area does not correspond to the pattern P2 (step S404: NO), the estimating unit 202 next performs the image in the divided area including the AF area. It is determined whether or not the movement corresponds to the pattern P3 (step S406). If the movement corresponds to the pattern P3 (step S406: YES), it is estimated that the subject is moving at the same distance from the photographer. (Step S407) When it does not correspond to the pattern P3 (Step S406: NO), it is estimated that the subject has not moved (Step S408).

  When the motion detection determination process by the estimation unit 202 in step S301 ends, the CPU block 1043 next checks whether or not the subject is estimated to have a motion by the motion detection determination process by the estimation unit 202 (step S302). When it is estimated that there is a motion in the subject (step S302: YES), the process proceeds to the next step S303. On the other hand, when it is estimated by the motion detection determination process that the subject has not moved (step S302: NO), the focus position detection process in the tracking AF mode is terminated without performing the subsequent processes.

  In step S303, the CPU block 1043 once ends the motion detection process by the motion detection unit 201 described above. Then, the CPU block 1043 performs subject tracking processing (step S304). Regarding subject tracking, template matching is performed using image information of the subject as a template while moving in the direction in which the subject has moved. FIG. 14 shows the movement of the tracking area that is the range for performing template matching. The moving direction of the subject is output by the motion detection process described above (here, it is assumed that the subject is moving in the lower left direction as shown in FIG. 14A), so that the tracking area is moved in that direction. As shown in FIG. 14B, the position where the pixel difference with the subject image data becomes the smallest in the tracking area is searched in the vertical and horizontal directions, and the position where the pixel difference with the subject image data becomes the smallest is It is determined that the position of the subject. If the pixel differences in all directions within the tracking area are larger than the reference value, matching is performed while moving the tracking area in the motion detection direction.

  Next, the CPU block 1043 moves the AF area to the subject position tracked by the tracking process in step S304 (step S305). Then, the focus position detection range setting unit 203 of the CPU block 1043 performs a process of setting a focus position detection range for performing an AF operation on this AF area (step S306).

  FIG. 15 is a flowchart showing details of the focus position detection range setting process by the focus position detection range setting unit 203 in step S306 of FIG. First, the focus position detection range setting unit 203 sets a reference range of the focus position detection range in the tracking AF mode (step S501). The reference range of the focus position detection range in the AF mode depends on the focal length of the digital still camera and the F value of the lens. In this embodiment, as shown in the table of FIG. 16, the focal length (Wide or Tele ) And the current position of the focus lens 42a, the reference range of the focus position detection range in the tracking mode is set. For example, when the focal length is Wide and the current position of the focus lens 42a is between 2.5 m from the infinite telephoto position (∞), the focus motor 42b has 10 pulses centered on the current position of the focus lens 42a. Is set as the reference range.

  Next, the focus position detection range setting unit 203 confirms whether or not the subject is estimated to have moved away from the photographer by the motion detection determination process by the estimation unit 202 described above (step S502), and the subject is the photographer. If it is estimated that the object is far from (step S502: YES), the number of pulses in the far direction is added to the reference range set in step S501 to obtain a focus position detection range (step S503). . On the other hand, if it is not estimated that the subject is moving away from the photographer (step S502: NO), it is confirmed whether the subject is estimated to be approaching the photographer (step S504), and the subject is photographed. Is estimated (step S504: YES), the number of pulses in the near direction is added to the reference range set in step S501 to obtain a focus position detection range (step S505). . On the other hand, when it is not estimated that the subject is approaching the photographer (step S504: NO), that is, it is estimated that the subject is moving at the same distance from the photographer or the subject is not moving. If so, the reference range set in step S501 is directly used as the focus position detection range without adding the number of steps (step S506).

  In this embodiment, the pulses added in step S503 and step S505 are determined according to the focal length (Wide or Tele) and the current position of the focus lens 42a as shown in the table of FIG. For example, when the focal length is Wide and the current position of the focus lens 42a is between 2.5 m from the infinite telephoto position (∞), if it is estimated that the subject is moving away, two pulses on the far side, If it is estimated that the subject is approaching, 4 pulses are added to the near side.

  FIG. 18 shows a driving method of the focus lens 42a when the focus position detection range is made variable according to the movement of the subject during AF in the tracking AF mode. As shown in FIG. 18, in this embodiment, the focus position detection range (the movement range of the focus lens 42a) is extended in the far side direction or the near side direction according to the movement of the subject during AF in the tracking AF mode. I am doing so. Thereby, even when the subject is moving in the depth direction of the screen, an appropriate AF operation can be realized without losing sight of the in-focus position.

  When the focus position detection range setting process by the focus position detection range setting unit 203 in step S306 ends, the focus position detection unit 203 of the CPU block 1043 then performs a focus lens by a start position movement process (step S307). The position 42a is moved to the movement start position. The movement start position is, for example, a position corresponding to ½ of the focus position detection range in the near direction from the current position of the focus lens 42a, and the addition pulse if there is the addition pulse in the near direction.

  Next, the focus position detection unit 204 performs lens driving processing (step S308), and moves the focus lens 42a step by step toward the far side in the focus position detection range. Then, an AF evaluation value acquisition process (step S309) is performed, and an AF evaluation value in the AF area is acquired at each moved position. Here, the movement distance for one step of the focus lens 42a is the same as that in the normal AF mode. When the focal distance is Wide, the focus motor 42b is driven one pulse at a time, and when the focal distance is Tele, the focus motor 42b is moved. While driving two pulses at a time, an AF evaluation value at each position is acquired. The focus position detection unit 204 repeatedly performs the lens driving process in step S308 and the AF evaluation value acquisition process in step S309 until the focus lens 42a reaches the end position of the focus position detection range (step S310: NO). When the focus lens 42a reaches the end position of the focus position detection range (step S310: YES), the process proceeds to the next step S311.

  In step S311, the focus position detection unit 204 performs a focus position determination process. In this in-focus position determination process, as in the in-focus position determination process in the normal AF mode, the above-described reliability evaluation is performed on the AF evaluation value acquired at each movement position of the focus lens 42a, and the AF evaluation is performed. Determine the peak position in the value. Here, when a reliable peak position is detected, the position of the focus lens 42a is stored in the local SRAM 1044 or the like as the focus position, and it is determined that the focus is OK. On the other hand, if no reliable peak position is detected, it is determined that the focus is NG.

  Finally, the CPU block 1043 performs area display processing (step S312) and ends the focus position detection processing in the tracking AF mode. In the area display process, as in the area display process in the normal AF mode, when the focus determination process in step S311 determines that the focus is OK, the focus frame F that clearly indicates the in-focus position is displayed on the finder image. When the image is superimposed and displayed on the LCD monitor 9 or the like, and it is determined as in-focus NG in the focus determination process in step S311, the finder image without the focus frame superimposed is displayed on the LCD monitor 9 or the like.

  In-focus position detection processing in the normal AF mode in step S107 in FIG. 5 (processing shown in the flowchart in FIG. 7) or in-focus position detection processing in tracking AF mode in step S108 (in the flowchart in FIG. 9). When the processing (shown) is completed, the CPU block 1043 next checks whether or not the in-focus position detection processing has achieved in-focus (step S109). Step S109: YES) Further, it is confirmed whether or not the focus position detection process in the tracking AF mode has been performed (step S110). When the focus is detected by the focus position detection process in the tracking AF mode (step S109: YES, step S110: YES), the CPU block 1043 sets the tracking flag to ON (step S111). The motion detection process once ended in the focus position detection process in the tracking AF mode is resumed (step S112).

  On the other hand, when the in-focus position detection process is in focus NG (step S109: NO), or when the in-focus position detection process in the normal AF mode is in focus (step S109: YES) Step S110: NO), the CPU block 1043 turns off the tracking flag (Step S113).

  Finally, the CPU block 1043 performs a focus position movement process (step S114), and moves the focus lens 42a to the position detected as the focus position in the focus position detection process. If it is determined that the in-focus position is determined to be in-focus NG, the focus lens 42a is moved to a position corresponding to the NG distance. Here, regarding the NG distance, a hyperfocal distance may be generally used, but in this embodiment, the focus lens 42a is moved to a position of 2.5 m, for example.

  19 to 21 show an image of a series of processes according to the present embodiment. FIG. 19 shows an example in which the subject is moved by the movement of the pattern P1, and FIG. 20 shows the pattern P2. FIG. 21 shows an example where the subject is moving due to the movement of the pattern P3, and FIG. 21 shows an example where the subject is moving due to the movement of the pattern P3. When the subject is moving as shown in (a) of each figure, if the AF area is set as shown in (b) of each figure at the timing when the release shutter SW1 is pressed, the division including the AF area is performed. The motion of the image in the block is detected as shown in FIG. Then, the tracking area is moved as shown in (d) of each figure to track the subject by template matching, and the AF area is moved to the position of the tracked subject as shown in (e) of each figure. , AF operation is executed. At this time, the focus position detection range during AF (the movement range of the focus lens 42a) is extended to the far side in the example of FIG. 19, and is extended to the near side in the example of FIG. In the example of FIG. 21, the focus position detection range during AF is not extended.

(Second embodiment)
Next, a second embodiment will be described. In the present embodiment, in the focus position detection process in the tracking AF mode shown in the flowchart of FIG. 9, the details of the motion detection determination process by the determination unit 202 in step S301 and the focus position detection range setting in step S306. The focus position detection range setting process performed by the unit 203 is different from that of the first embodiment. Other than that, the second embodiment is the same as the first embodiment, and only the differences from the first embodiment will be described below.

  FIG. 22 is a flowchart illustrating details of the motion detection determination process performed by the determination unit 202 according to the second embodiment. In the motion detection determination process of the second embodiment, the estimation unit 202 first performs a motion detection area search process (step S601). This is to estimate the movement of the subject or the photographer by determining which of the nine image areas to be subjected to the motion detection process is the image movement direction in each image area.

  Specifically, the estimating unit 202 first determines whether or not movement in the same direction is detected in all nine divided regions (step S602). This assumes a scene in which the photographer changes the composition of the subject by moving the digital still camera. FIG. 23 shows the movement pattern of each divided area when the photographer moves the digital still camera to change the composition of the subject. As shown in FIGS. 23A to 23H, when the photographer moves the digital still camera and changes the composition of the subject, movement in the same direction is detected in all nine divided regions. The estimation unit 202 confirms whether or not movement in the same direction is detected in all the divided areas. If movement in the same direction is detected in all the divided areas (step S602: YES), the photographer Is moving the digital still camera and presuming that the composition of the subject has been changed (step S603).

  On the other hand, when the movement in the same direction is not detected in all the divided areas (step S602: NO), the estimation unit 202 does not detect the movement in the divided areas including the AF area and includes the AF area. It is determined whether or not movement in the same direction is detected in other divided areas than the divided areas (step S604). This assumes a scene where the photographer is taking a panning shot of a moving subject. FIG. 24 shows a movement pattern of each divided area when the photographer performs a panning shot of a moving subject. As shown in FIGS. 24A to 24C, the movement of each divided area in the case of panning is performed in a direction opposite to the gravitational direction (as image data) in other divided areas including the AF area. Is a pattern in which the movement in the upward direction is detected (hereinafter referred to as pattern P4), and other divided areas other than the divided areas including the AF area, as shown in FIGS. A pattern (hereinafter referred to as a pattern P5) in which movement in the direction of gravity (downward direction as image data) is detected, and a divided area including an AF area as shown in FIGS. The pattern can be classified into patterns (hereinafter referred to as pattern P6) in which movement in the left-right direction is detected in other divided areas.

  The estimation unit 202 confirms whether movement in the same direction is detected in other divided areas other than the divided area including the AF area, and determines in the same direction in the other divided areas other than the divided area including the AF area. If a motion is detected (step S604: YES), it is determined whether the motion of the image corresponds to the pattern P4 (step S605). If the pattern P4 is satisfied (step S605: YES), it is estimated that the photographer is taking a panning shot of the approaching subject (step S606). On the other hand, when the motion of the image does not correspond to the pattern P4 (step S605: NO), the estimation unit 202 determines whether or not the motion of the image corresponds to the pattern P5 (step S607). If the pattern P5 corresponds to the pattern P5 (step S607: YES), it is estimated that the photographer is taking a panning shot of the away object (step S608). If the image motion does not correspond to the pattern P5, that is, When it corresponds to the pattern P6 (step S607: NO), it is estimated that the photographer is taking a panning shot of the subject that is moving laterally (step S609).

  On the other hand, when the movement in the same direction is not detected in other divided areas other than the divided area including the AF area (step S604: NO), the estimating unit 202 determines other than the divided areas including the AF area. It is determined whether the direction of motion detected in the divided area is a direction toward or away from the divided area including the AF area (step S610). This assumes a scene in which the photographer is moving in the direction of approaching and moving away from a stationary subject. FIG. 25 shows a movement pattern of each divided area when the photographer moves in a direction of approaching and separating from a stationary subject. When the photographer moves in this manner, the movement of each divided area is directed to the divided area including the AF area in another divided area other than the divided area including the AF area, as shown in FIG. A pattern in which the movement in the direction is detected (hereinafter referred to as pattern P7) and a divided area including the AF area in a divided area other than the divided area including the AF area as shown in FIG. The pattern can be classified as a pattern in which movement in a direction away from the region is detected (hereinafter referred to as pattern P8).

  When the direction of motion detected in another divided area other than the divided area including the AF area is a direction toward or away from the divided area including the AF area (step S610: YES), the estimation unit 202 Determines whether the movement of the image corresponds to the pattern P7 (step S611). If the pattern P7 is satisfied (step S611: YES), it is estimated that the photographer is moving away from the subject (step S612). On the other hand, if the movement of the image does not correspond to the pattern P7, that is, if it corresponds to the pattern P8 (step S611: NO), it is estimated that the photographer is moving toward the subject (step S613).

  On the other hand, if no movement in the direction toward or away from the divided area including the AF area is detected in other divided areas other than the divided area including the AF area (step S610: NO), the estimating unit 202 Focusing on the divided area including the AF area, as in the first embodiment, which of the patterns P1 to P3 shown in FIG. 13 corresponds to the image movement in the divided area including the AF area? Is estimated, it is estimated whether the subject is moving, whether it is moving in a direction approaching the photographer as a distance, or moving away from the photographer.

  That is, the estimation unit 202 first determines whether or not the image motion in the divided area including the AF area corresponds to the pattern P1 (step S614), and if it corresponds to the pattern P1 (step S614: YES). It is estimated that the subject is moving in the direction approaching the photographer (step S615). On the other hand, when the direction of image movement in the divided area including the AF area does not correspond to the pattern P1 (step S614: NO), the estimating unit 202 next performs the image in the divided area including the AF area. It is determined whether or not the movement corresponds to the pattern P2 (step S616). If the movement corresponds to the pattern P2 (step S616: YES), it is estimated that the subject is moving away from the photographer (step S616). S617). On the other hand, if the direction of image movement in the divided area including the AF area does not correspond to the pattern P2 (step S616: NO), the estimating unit 202 then performs the image in the divided area including the AF area. It is determined whether or not the movement corresponds to the pattern P3 (step S618). If the movement corresponds to the pattern P3 (step S618: YES), it is estimated that the subject is moving at the same distance from the photographer. (Step S619) If not corresponding to the pattern P3 (Step S618: NO), it is estimated that neither the photographer nor the subject has moved (Step S620).

  FIG. 26 is a flowchart showing details of the focus position detection range setting process by the focus position detection range setting unit 203 of the second embodiment. In the focus position detection range setting process of the second embodiment, the focus position detection range setting unit 203 first sets a reference range of the focus position detection range in the tracking AF mode (step S701). As in the first embodiment, the reference range of the focus position detection range in the AF mode is as shown in the table of FIG. 16 depending on the focal length (Wide or Tele) and the current position of the focus lens 42a. Set to. For example, when the focal length is Wide and the current position of the focus lens 42a is between 2.5 m from the infinite telephoto position (∞), the focus motor 42b has 10 pulses centered on the current position of the focus lens 42a. Is set as the reference range.

  Next, the focus position detection range setting unit 203 confirms whether or not it is estimated that the photographer moves the digital still camera and changes the composition of the subject by the above-described motion detection determination process (step S702). If it is estimated that the subject is moving away from the photographer (step S702: YES), the reference range set in step S701 is directly used as the focus position detection range (step S703).

  On the other hand, when it is not estimated that the photographer moves the digital still camera and changes the composition of the subject (step S702: NO), the in-focus position detection range setting unit 203 performs the panning by the photographer. It is confirmed whether or not it is estimated (step S704). If it is estimated that the photographer is taking a panning shot (step S704: YES), it is confirmed whether the subject is a panning shot (step S705), and the approaching subject is panned. If it is estimated (step S705: YES), the number of pulses in the near direction is added to the reference range set in step S701 to obtain a focus position detection range (step S706). On the other hand, if it is not a panning shot of a subject that is approaching (step S705: NO), it is confirmed whether or not the panning shot of a subject that is moving away (step S707), and it is estimated that the subject that is moving away is panning. If so (step S707: YES), the number of pulses in the far direction is added to the reference range set in step S701 to obtain the in-focus position detection range (step S708). In addition, when it is not a panning shot of a subject that is moving away, that is, when it is estimated that a subject that is moving laterally is panning (step S707: NO), the reference range set in step S701 is directly matched. The focus position detection range is set (step S703).

  If it is not estimated that the photographer is taking a panning shot (step S704: NO), the in-focus position detection range setting unit 203 is a direction in which the photographer approaches and moves away from a stationary subject. It is confirmed whether it is estimated that it has moved to (step S709). If it is estimated that the photographer is moving in the direction of approaching and separating from the stationary subject (step S709: YES), it is confirmed whether or not the photographer is moving in the direction away from the subject (step S710). ) If it is estimated that the photographer is moving away from the subject (step S710: YES), the number of pulses in the far side is added to the reference range set in step S701 to The focus position detection range is set (step S708). Further, when the movement is not in the direction away from the subject, that is, when it is estimated that the photographer is moving toward the subject (step S710: NO), the near direction with respect to the reference range set in step S701. Are added to obtain the in-focus position detection range (step S706).

  If it is not estimated that the photographer is moving in the direction of approaching or separating from the stationary subject (step S709: NO), the focus position detection range setting unit 203 determines that the subject is the photographer. Whether it is estimated that the subject is moving away from the photographer (step S711). If it is estimated that the subject is moving away from the photographer (step S711: YES), the reference range set in step S701 is determined. The number of pulses in the far side direction is added to obtain a focus position detection range (step S708). On the other hand, if it is not estimated that the subject is moving away from the photographer (step S711: NO), it is confirmed whether the subject is estimated to be approaching the photographer (step S712), and the subject is photographer. Is estimated (step S712: YES), the number of pulses in the near direction is added to the reference range set in step S701 to obtain a focus position detection range (step S706). . On the other hand, if it is not estimated that the subject is approaching the photographer (step S712: NO), that is, the subject has moved the same distance from the photographer, or neither the photographer nor the subject has moved. If it is estimated, the reference range set in step S701 is used as the in-focus position detection range as it is without adding the number of steps (step S703).

  As for the pulses added in step S706 and step S708, as shown in the table of FIG. 17, according to the focal length (Wide or Tele) and the current position of the focus lens 42a, as in the first embodiment. decide. For example, when the focal length is Wide and the current position of the focus lens 42a is between 2.5 m from the infinity telephoto position (∞), the number of pulses added on the far side is 2, and the number of pulses added on the near side is 4 pulses. As described above, in the present embodiment, during the AF in the tracking AF mode, the focus position detection range (the movement range of the focus lens 42a) is set to the far side direction or the near side direction according to the movement of the photographer or the movement of the subject. To extend. Accordingly, even when the subject is relatively moving in the depth direction of the screen due to the movement of the photographer or the subject, an appropriate AF operation can be realized without losing sight of the in-focus position.

  27 to 29 show an image of a series of processes according to the present embodiment. FIG. 27 shows an example in which the photographer moves the digital still camera to change the composition of the subject. FIG. FIG. 29 shows an example in the case where the photographer is taking a panning shot of a subject that is moving away. FIG. 29 shows an example in which the photographer is moving toward the subject. (A) of each figure has shown typically the image of each condition. When the AF area is set as shown in (b) of each figure at the timing when the release shutter SW1 is pressed, the movement of the image in the divided block including the AF area is detected as shown in (c) of each figure. . Then, the tracking area is moved as shown in (d) of each figure to track the subject by template matching, and the AF area is moved to the position of the tracked subject as shown in (e) of each figure. , AF operation is executed. At this time, the focus position detection range during AF (the movement range of the focus lens 42a) is extended to the far side in the example of FIG. 28 and extended to the near side in the example of FIG. In the example of FIG. 27, there is no extension of the focus position detection range during AF.

  As described above in detail with reference to specific examples, in the digital still camera according to the present embodiment, the CPU block 1043 in the processor 104 is output in time series from the CCD 101, and passes through the F / E-IC 102. Then, the motion of the image is detected based on the difference between the plurality of image data input into the processor 104 (motion detection unit 201), and the motion of the subject or the photographer is estimated based on the detected motion of the image ( Estimator 202). Then, in accordance with the estimated movement of the subject or the photographer, focus position detection, that is, the movement range of the focus lens 42a is set (focus position detection range setting unit 203), and the focus lens is set within the set focus position detection range. The focus position is detected while moving 42a (focus position detection unit 204). Therefore, even when the subject moves relatively in the depth direction of the screen due to the movement of the photographer or subject, the AF operation is appropriately executed without losing sight of the in-focus position, and the subject position is properly focused. You can shoot a good image.

  The specific embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments as they are, and may be embodied by modifying constituent elements without departing from the scope of the invention in the implementation stage. can do. For example, the configuration and operation of the digital still camera according to the embodiment are merely examples, and various modifications can be made depending on the application and purpose.

42a Focus lens 42b Focus motor 45 Motor driver 101 CCD
102 F / E-IC
104 Digital Still Camera Processor 1043 CPU Block 201 Motion Detection Unit 202 Estimation Unit 203 Focus Position Detection Range Setting Unit 204 Focus Position Detection Unit

Japanese Examined Patent Publication No. 39-5265 JP 2009-175442 A JP-A-4-158322

Claims (11)

A focus lens,
An image sensor that receives light incident through the focus lens and outputs image data;
Motion detection means for detecting the motion of an image based on a difference between a plurality of image data output in time series from the imaging device;
Estimating means for estimating the movement of the subject or the photographer based on the movement of the image detected by the movement detecting means;
A moving range setting means for setting a moving range of the focus lens in accordance with the movement of the subject or the photographer estimated by the estimating means;
In-focus position detecting means for detecting an in-focus position with respect to the subject position of the image by moving the focus lens in the optical axis direction within the movement range set by the movement range setting means. An imaging apparatus characterized by that. The motion detection means divides the image data output from the image sensor into a plurality of divided areas, detects the movement of the image for each divided area,
The estimating means estimates a relative movement between the subject and the photographer based on the position of the divided area where the movement is detected by the movement detecting means and the direction of the movement in the divided area;
The movement range setting means may be configured such that when the relative movement between the subject and the photographer estimated by the estimation means is a movement in a direction in which the distance between the subject and the photographer becomes small, the subject and the photographer Compared to the case where the distance between the subject and the photographer does not change, the movement range of the focus lens is increased in the near side direction, and the relative movement between the subject and the photographer estimated by the estimation unit is When the movement in the direction in which the distance between the subject and the photographer increases, the movement range of the focus lens is increased in the far side direction compared to the case where the distance between the subject and the photographer does not change. The imaging apparatus according to claim 1. The estimation means detects the motion to the photographer when the motion is detected only in the divided area including the subject position by the motion detecting means and the direction of the motion detected in the divided area including the subject position is the gravitational direction. Presuming that they are approaching,
The movement range setting means increases the movement range of the focus lens in the near side direction when the estimation means estimates that the subject is approaching the photographer compared to when the subject is not moving. The imaging apparatus according to claim 2, wherein: The estimation means detects the subject when the motion detection means detects the motion only in the divided area including the subject position and the direction of the motion detected in the divided area including the subject position is opposite to the gravitational direction. Is estimated to be away from the photographer,
When the estimation unit estimates that the subject is moving away from the photographer, the movement range setting unit increases the movement range of the focus lens in the far side direction compared to the case where the subject is not moving. The imaging apparatus according to claim 2, wherein: The estimating means detects motion in the same direction in a plurality of divided areas other than the divided area including the subject position by the motion detecting means, and in a plurality of divided areas other than the divided area including the subject position. If the detected direction of motion is the direction of gravity, it is assumed that the photographer is taking a panning shot of the subject that is approaching,
The movement range setting means compares the movement range of the focus lens with that when the subject is not moving when the estimation means estimates that the photographer is taking a panning shot of the subject that is approaching. The imaging device according to claim 2, wherein the imaging device is enlarged in the near direction. The estimating means detects motion in the same direction in a plurality of divided areas other than the divided area including the subject position by the motion detecting means, and in a plurality of divided areas other than the divided area including the subject position. If the detected direction of motion is opposite to the direction of gravity, assume that the photographer is taking a panning shot of the subject moving away,
The movement range setting means compares the movement range of the focus lens with that when the subject is not moving when the estimation means estimates that the photographer is taking a panning shot of a subject that is moving away. The image pickup apparatus according to claim 2, wherein the image pickup apparatus is enlarged in a far side direction. The estimation unit is configured to detect the movement of the photographer toward the subject when movement in a direction away from the divided region including the subject position is detected in the plurality of divided regions other than the divided region including the subject position by the motion detecting unit. Estimated to have moved,
The movement range setting means, when the estimation means estimates that the photographer is moving toward the subject, the movement range of the focus lens is closer than that when the photographer is not moving. The imaging apparatus according to claim 2, wherein the imaging apparatus is increased in a lateral direction. The estimation unit causes the photographer to move away from the subject when movement in a direction toward the divided region including the subject position is detected in the plurality of divided regions other than the divided region including the subject position by the motion detection unit. Presumed moving in the direction,
The movement range setting means, when the estimation means estimates that the photographer is moving in a direction away from the subject, the movement range of the focus lens is compared with the case where the photographer is not moving. The imaging apparatus according to claim 2, wherein the imaging apparatus is increased in the far side direction.   The estimation means estimates that the distance between the subject and the photographer has not changed when movement in the same direction is detected in all divided areas by the motion detection means. Item 3. The imaging device according to Item 2. An in-focus position detection method executed in an imaging device including a focus lens and an image sensor that receives light incident through the focus lens and outputs image data,
Detecting a movement of an image based on a difference between a plurality of image data output in time series from the imaging device;
Estimating the movement of the subject or the photographer based on the detected movement of the image;
Setting a moving range of the focus lens in accordance with the estimated subject or photographer movement;
A focus position detecting method comprising: moving the focus lens in the optical axis direction within a set movement range to detect a focus position that is in focus with respect to the subject position of the image. An imaging apparatus comprising: a focus lens; and an image sensor that receives light incident through the focus lens and outputs image data;
A function of detecting the movement of an image based on a difference between a plurality of image data output in time series from the imaging device;
A function that estimates the movement of the subject or the photographer based on the detected movement of the image,
A function for setting the moving range of the focus lens in accordance with the estimated subject or photographer movement;
An in-focus position detection program for realizing a function of moving the focus lens in the optical axis direction within a set movement range to detect an in-focus position with respect to a subject position of an image.

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